I would download this book, but I already have it in my library--have had it in my library since high school, actually. If you're not familiar with Elements of Style by William Strunk, here's an opportunity to download the first edition for free. E.B. White became a coauthor in later editions--that's right....the E.B. White of Charlotte's Web fame.
Here is the link to Rob Parnell's blog, then click on "Download: Elements of Style.
I've used this book more than any other guide to composition. Strunk's advice to "omit needless words" is just as important now as it was in 1957 when Elements first came out.